Concrete finishing trowel



2,833,188 CONCRETE FINISHING TROWEL Bernhard D. Wilkens, Secaucus, N. J. 1 Application November 15,1955, Serial N... 547,1 14 2 Claims. (CI. 94-45 This invention relates to an automatic trowel for finishing concrete surfaces and, more particularly,.it relates to an automatic trowel which can be operated at a distance from the surface to be finished and does not require a skilled mechanic for its operation.

In the finishing of concrete or other plastic surfaces today the generally accepted technique is to finish the material by hand troweling with a skilled mechanic generally down on his hands and knees doing the work. In the case of concrete, it is necessary, after placingth'e concrete, to wait for at least several hours before beginning the finishing operation, in order to permit the concrete to harden or set sufiiciently to hold the weight of the finisher. The finishing operation is a laborious one, usually done with a standard trowel of about /3 square foot surface area and usually requiring a high degree of skill from the finisher. Working down on the concrete does not afford the finisher a suflicient perspective to enable him to turn out a completely level job irrespective of his skill. Another difliculty arising in recent years is the fact that a skilled mechanic, after working for a lifetime on the wet concrete on his knees, is forced to retire from his trade at an early age as he often develops knee and leg troubles and he just cannot perform this type of difficult work for too long a period. Trowels havebeen devised from time to time to overcome some of these difiiculties, but as far as I know none are in use and all were dependent on a skilled operator.

It is therefore an object of this invention to devise an automtic trowel that will finish, at one time, far larger surfaces than currently known trowels.

It is a further object to devise a trowel that can be operated at a distance from the work to be finished and can be operated by an unskilled laborer.

It is yet a further object of this invention to provide a trowel that will permit earlier finishing of concrete surfaces than is now possible.

These and yet other objects will be developed as this specification proceeds.

In summary, this invention accomplishes these objects by providing a balanced dual-trowel which will auto'matically raise by a predetermined amount the forward edge of each trowel blade as it is moved over the surface to be finished, the rise being independent of the operator.

Each trowel blade of the dual-trowel is about three feet square in surface area, or six feet square total, compared with the normal standard of about /3 square foot, and is operated at a distance by a long pole connected'to the trowel-holding device.

Reference is now made to the drawings for a more detailed description of a preferred embodiment of this invention.

Fig. 1 is a side elevation of the trowel showing, in phantom, the two working positions.

Fig. 2 is a rear elevation of the trowel, through section 2-2 of Fig. l with links 27, 28 omitted.

Fig. 3 is a section through section 3-3 of Fig. 1.

S ates. P en Fig. 4 is an idealized showing of an alternative arrangement for the pivoted hanger.

Fig. 5 is an idealized showing of a plan view of the trowel with attached blades and boards.

Figures 6 and 7are schematic diagrams of the trowe in the push and pull positions.

More particularly in the drawings, the trowel 11 comprises right frame 12, left frame 13, upper cross-arm 14 and lower cross-arm 15. The upper cross-arm 14 is bolted to the right frame, with bolt 16 and nut 17. The upper cross-arm 14 is bolted to the left frame with bolt 18 and nut 19.

hollowed-out section 22 which serves as a be described later.

The lower cross-arm 15 comprises two sections 15a and 1512. Section 15a spans between one side of theright frame 12 to a similar side of the left frame 13. Section' 15b spans from the opposite side of right frame 12to' the similar side of left frame 13. Both sections of lower cross-arm 15 are bolted in between the respective frames by bolt 23 with nut 24 and bolt 25 with nut 26. Thus it p can be seen that the upper cross-arm spans betweenthe two frames and is bolted to each of them and the lower cross-arm spans between the two frames and is bolted to each of them. The lower cross-arms have an upstanding leg 27 from the upper portion of which is suspended pivoted hanger 28. This pivoted hanger-28 is bolted be.-

' nates in threaded receiver 34 which is canted at a 7 angle with the handle extension 33.

In operation, if the handle is pushed the pivoted hanger 28 moves in its lowermost portion to the left as shown in Fig. 1. This causes through pivoted pin 31 a displacement of the upper cross-arm 14 to the right, which in turn causes both the left and right frames to tilt towards the right. If the handle extension 33 is pulled, the reverse operation occurs and the frames are tilted to the left.

Attached to the bottom of each frame, as shown in idealized view 5, is a short, preferably stainless steel blade bolted through holes 36 and 37 shown in Figure 2. These stainless steel blades 38 should preferably be about 3 to 4 inches in width and about 18 inches in length. These dimensions are not critical, however. Further attached to each of the stainless steel blades 38 is a piece of marine plywood 41 about 6 inches in width and 6 feet long, thus providing a large total troweling surface. It can be seen from the operation above described that I when the handleextension 33 is pushed and the frames are tilted to the right, the stainless steel blades 38 are tilted accordingly so that the leading edge in the direction of the push is raised off the concrete. When the handle extension 33 is pulled the frames are tilted counterclockwise and the blades are tilted accordingly, the opposite edge of the blades, that is, the edge nearest to the direction of pull, is tilted upwardly and raised off the concrete. In operation then the trowel must automatically tilt its blades depending on the direction of movement and cannot dig into the concrete that it is working.

When working close to a wall it will be seen that the blades have one position when pushed up to the wall.

' Patented May 6, 1958'? It is bolted to its respective framesthrough upstanding sections 20 and 21 on each frame. The upper cross-arm 14 has positioned at its mid point a pivot, as

rear edge to be depressed. andto press down on the concrete right up to the very edge of. the wall.

To control the angle that the blades will assume there is provided in each side of the lower cross-arms 15 a stop 48 against, which the pivoted'han ger- 28. strikes when it is pushed or pulled .andits distance of travel is thus controlled. As a further modification in order to provide a control over the distance of travel of thepivoted hanger 28there is shown in Fig. 4 a modified pivoted hanger .128 which has mounted thereonwing-like extensions 39- which strike the upperportion ofv the lower cross-arm 15 when the pivoted hanger 128 is pivoted.

The trowel is normally expected to be used with a long wooden handle. inserted in .the internal threads (not shownlof threaded receiver 34. Of. course any number 4 the device may be moved back and forth very swiftly across the area to beworked;

This application has been directed to the use of a dualtrowel blade arrangement, but it is of course obvious to use the teachings of this invention for more than two trowel blades by the expedient of extending the crossarms a suflicient length to accommodate the additional trowels.

the. size ofthe work and the distance ,that the operator i must stand from it. The handle extension 33 is pivoted from the lower portion of. pivoted hanger 28 and is thus able to move in a vertical up-and-down direction inside the frame. This up-and-down movement permits the operator to' work at. a comfortable height so that he can either holdthe handle up high or down low depending on hispreference. Since it is loosely pivoted, it means that the device is independent of the operator in this respect and he. cannot.accidentally lift it off the concrete or change the angle of the blades without making a deliberate efiortto do so. j p i In addition to operating as a trowel, it has been found thatthis device will also operate as a float. A further advantage is that, because of the large area of the blades with their attached wood portions, the device will act as a leveling device and serve to smooth out minor deficiencies in.the surface of the concrete, particularly because I claim:

1. An automatic trowel comprising a pair of trowel blades, a frame fixedly attached to each blade, an upper cross-arm pivotally attached to each frame near its top, a lower cross-arm pivotally attached to each frame near its bottom, an arm pivotally connected to the upper crossarm intermediate the two frames, the lower cross-arm having a central upward projection pivotally mounted on said pivoted arm, and a handle pivotally connected to the lower end portion of said pivoted arm, whereby move ment of said handle in either direction will automatically raise the trowel blades in the direction of movement.

2. A trowel according to claim 1, in which stops are provided on one of the cross-arms in the path of travel of the pivoted arm.

References Cited in the file of this patent UNITED STATES PATENTS 973,688 Nicholas. Oct. 25, 1910 1,021,557 Runner Mar. 26, 1912 1,713,513 Abram May 21, 1929 2,134,689 French 4... Nov. 1, 1938 2,293,962 Baily Aug. 25, 1942 2,351,278 Mathews June 13, 1944 2,453,510 Jackson Q.-- Nov. 9, 1948 2,603,132, Miller July 15, 1952 

